1. Field of the Invention
The present invention relates to a separable blade for a wind turbine with a lightning protection device.
2. Description of Related Art
These days, a wind turbine is in practical use. In recent years, in consideration of increasing cases of installing wind turbines at a mountainous area or the like, various proposals have been made for protecting a blade of a wind turbine from lightning.
What is proposed as one example is a technology in which a lightning receptor is placed at an edge part of a blade of a wind turbine, and an electrical conduction wire which extends from the lightning receiving unit up to the edge part of the blade is placed within the blade or on the blade surface, so that the lightning current is guided to a hub through these lightning receiving unit and the electrical conduction wire (for example, see p. 34 IEC/TC88, “Wind turbine generator systems-Part24:Lightning protection for wind turbines”, IEC61400-24, Ed.1, IEC, Oct. 22, 1999).
Meanwhile, in conjunction with a request of large-sizing a wind turbine these days, there is an emerging problem in transportation of wind turbine blades. In order to solve such a problem, what is proposed is a technology in which a large-sized blade is divided in its longitudinal direction for transportation, and the divided pieces of blades are joined by using a junction portion made of metal, such as a barrel nut, a tension bolt or the like, at a setting location.
However, if such a separable blade is adopted, there is a new emerging problem that the blade can be broken when lightning strikes the above-described joining member made of metal.